Synthesis of Tobermorite Structure with Non-traditional Silica Components

Vit Cerny, Jan Fleischhacker, Magdalena Kocianova, Rostislav Drochytka


The main aim of the article is research of kinetics of creation of calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH) phases in the autoclaved aerated concrete in dependence on type of raw materials. Regarding materials, this will be unique combinations of lime with fly ash, quartz sand or silica fume. The aim will be to prove the influence of ratio of individual types of materials on the CSH phase to determine optimal combinations of raw materials. The research focuses first on detailed analysis of the used materials. Next focus is kinetics of the creation of microstructures of silicate phases under ideal conditions of small-sized autoclave reactors (250 ml, 190 °C, 1.3 MPa). The produced samples are further analysed using of x-ray diffraction (XRD) and scanning electron microscopy (SEM) for qualitative valuation of created microcrystalline phases. The results show that the most suitable non-traditional silica component is ash from coal combustion. The optimal combination of amorphous and crystalline silicon in combination with Al2O3 provided the highest proportion of synthesized tobermorite even in more economical autoclaving variants.


autoclaved aerated concrete; tobermorite; calcium sulfate; fly ash; silica fume.

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